Problem 12-123

It is difficult to find the order of reactant [B] since the concentration of [A] is different in each experiment.

exp [Ao] [Bo] Initial rate
(1) 0.12 0.18 3.46x10-2
(2) 0.060 0.12 1.15x10-2
(3) 0.030 0.090 4.32x10-2
(4) 0.24 0.090 3.46x10-2

In this case, find the order of [A] by using reactions (3) and (4) since [B] is constant.

rate(4) = k[A]n[B]m
rate(3) = k[A]n[B]m

At his point you must be able to find the order of "n", then, you repeat the process with any other reaction by including the actual n value (known) in your calculations:

rate(1) = k[A1]known[B]m
rate(2) = k[A2]known[B]m

which becomes (without k):

rate(1) x [A2]known = [B]m
rate(2) x [A1]known = [B]m

the left part of the equation is known and can be used to find the order "m" value.